Following a report that T-Mobile is canceling vacations for store employees between September 20 and September 22, another story has affirmed that rival AT&T is now following suit. Specifically, the carrier is said to be blacking out vacation days for the second half of September, seemingly in preparation for the iPhone 5S/5Claunch date.

That’s a tell-tale sign of an impending iPhone launch: carriers want to ensure enough staff is on hand to handle an influx of customers at launch. Notably, AT&T did the same last year ahead of the iPhone 5 launch, as well as every single year starting with the original iPhone launch back in 2007.

Putting these pieces together, new iPhones are very likely going on sale in the United States and a few major international markets on Friday, September 20, which would be ten days after the official unveiling…